Influence of the hydrogen bond on the N-H stretching frequencies in amino-acids

The spectra of glycine, its addition compounds and other amino-acids exhibit Raman lines in the region from 3250 cm.−1 to 2500 cm.−1 It has been shown that these lines cannot be assigned to N-H...O stretching vibrations, where the N atom has the covalency of three, but to N+-H...O stretching vibration where the N atom has the covalency of four. Using the data obtained with triglycine sulphate which has the largest number of N+-H...O bonds and whose H bond lengths are known, the correlation curve giving the relation between the N+-H...O stretching frequencies and the corresponding H bond lengths has been drawn. Using this correlation curve, the N+-H...O stretching frequencies appearing inα-glycine,γ-glycine, diglycine hydrochloride, diglycine hydrobromide,l-asparagine monohydrate anddl-alanine have been satisfactorily accounted for on the basis of the known hydrogen bond lengths in these substances.

Raman spectrum of ethyl chloroacetate

The Raman spectrum of ethyl chloroacetate has been studied at 13° C., 28° C. and 78° C. The carbonyl frequency was found to be split up into two due to the presence of rotational isomers. The higher frequency line due to thecis isomer was found to decrease in intensity with temperature. It appears that the gauche isomer will predominate in the vapour state. Altogether thirty-eight Raman lines have been recorded. Reasonable assignments for the observed Raman lines were made in comparison with ethyl acetate spectrum.

The emission spectrum of bismuth monofluoride BiF—‘A’ system

The observation of (A-X) system of BiF has been extended up to λ 5316 and twenty new bands belonging to this system have been recorded. The band heads could be represented by the following equation: {Mathematical expression} Seven other faint bands in the region λ 5316-5492 have also been reported, which, however, could not be classified. By our analysis of the present data and from known thermochemical data it has been deduced that the ground state dissociation energy is, in all probability, around 20000 cm.-1 (∼2·5 ev.) and that the dissociation products are the normal Bi and F atoms. The dissociation energy of the upper state and the correlation rules have been used to show that the dissociation products in the upper state are very likely to be Bi atom in the excited state2D3/2 and F atom in its ground state (2P3/2).

Spectrophotometric and potentiometric investigations of copper (II)-ethanolamine complexes - Part II. Monoethanolamine (Analysis of mixed hydroxy complexes with polarographic evidence)

Potentiometric, spectrophotometric and polarographic evidence has been presented for the formation of mixed hydroxy complexes in coppermonoethanolamine system. A method has been developed for the analysis of Bjerrum formation curves taken in presence of 0·1, 0·2, 0·5 and 1·0 M monoethanolammonium ion with respect to hydroxy complexes. The formation of CuAOH+, CuA2OH+ and CuA3OH+ is shown and the corresponding stability constants are calculated at different concentrations of MEA ion. Curves showing the distribution of pure and hydroxy complexes at various pA values in solutions containing different concentrations of MEA ion have also been given.

Flow of an electrically conducting non-newtonian fluid between two rotating coaxial cones in the presence of external magnetic field due to an axial current

Bhatnagar and Rathna (Quar. Journ. Mech. Appl. Maths., 1963,16, 329) investigated the flows of Newtonian, Reiner-Rivlin and Rivlin-Ericksen fluids between two rotating coaxial cones. In case of the last two types of fluids, they predicted the breaking of secondary flow field in any meridian plane. We find that such breaking is avoided by the application of a sufficiently strong azimuthal magnetic field arising from a line current along the axis of the cones.

Detection of a periodic structure hidden in random background: the role of signal amplitude in the matched filter detection method

The matched filter method for detecting a periodic structure on a surface hidden behind randomness is known to detect up to (r(0)/Lambda) gt;= 0.11, where r(0) is the coherence length of light on scattering from the rough part and 3 is the wavelength of the periodic part of the surface-the above limit being much lower than what is allowed by conventional detection methods. The primary goal of this technique is the detection and characterization of the periodic structure hidden behind randomness without the use of any complicated experimental or computational procedures. This paper examines this detection procedure for various values of the amplitude a of the periodic part beginning from a = 0 to small finite values of a. We thus address the importance of the following quantities: `(a)lambda) `, which scales the amplitude of the periodic part with the wavelength of light, and (r(0))Lambda),in determining the detectability of the intensity peaks.

Raman spectrum of hydroxylamine hydrochloride (NH3OH.Cl)

The Raman spectrum of hydroxylamine hydrochloride (NH3OH.Cl) in the form of a single crystal has been photographed usingλ 2536·5 excitation. 32 Raman lines with frequency shifts 40, 57, 78, 88, 111, 125, 135, 156, 187, 217, 250, 330, 550, 575, 1004, 1168, 1204, 1470, 1496, 1565, 1590, 1979, 2636, 2710, 2750, 2789, 2926, 2970, 3000, 3050, 3141 and 3220 cm.−1 have been recorded. Of these, the first 8 low-frequency lines belong to the external oscillation, while the four lines at 187, 217, 250 and 330 cm.−1 should be attributed to the vibrations of the hydrogen bond valence vibrations. The remaining Raman lines have been assigned to the vibrations of the NH3OH ion. The O-H and N-H stretching vibrations are very much influenced by the presence of the hydrogen bonds in the crystal.

Cubic and ultimate groups of complete symmetry

It is shown that the systems of definite actions described by polar and axial tensors of the second rank and their combinations during the superposition of their elements of complete symmetry with the elements of complete symmetry of the "grey" cube, result in 11 cubic crystallographical groups of complete symmetry. There are 35 ultimate groups (i.e., the groups having the axes of symmetry of infinite order) in complete symmetry of finite figures. 14 out of these groups are ultimate groups of symmetry of polar and axial tensors of the second rank and 24 are new groups. All these 24 ultimate groups are conventional groups since they cannot be presented by certain finite figures possessing the axes of symmetry {Mathematical expression}. Geometrical interpretation for some of the groups of complete symmetry is given. The connection between complete symmetry and physical properties of the crystals (electrical, magnetic and optical) is shown.

Reactions with disulphur monoxide solutions obtained by the reduction of cupric oxide by elemental sulphur

When the products of reaction between elemental sulphur and copper oxide at elevated temperature in vacuum are bubbled through chilled inert organic solvents like carbontetrachloride, orange-yellow solutions were obtained indicating the presence of lower oxide of sulphur. This lower oxide has been found to be disulphur monoxide as shown by three different types of reactions; (1) Mercury decomposition, (2) Reaction with hydrogen iodide and hydrolytic reaction in an alkaline homogeneous medium.

The change of complete symmetry of the crystals during the phase transitions in ferroelectrics and ferromagnetics

The extension of the superposition principle of the symmetries (P. Curie principle of symmetry) for the case of complete symmetry is given. The enumeration of all crystallographical groups of complete symmetry is presented, the number of elements having complete symmetry for each class of the crystals being indicated. The change of complete symmetry of the crystals under the phase transitions is obtained by superimposing the elements of complete symmetry of polar or axial vectors on the one hand, and the elements of complete symmetry of the crystals on the other. The tables of complete symmetry changes for the cubic, rhombic, monoclinic and triclinic crystals during the ferroelectric and ferromagnetic phase transitions are given.

Raman spectrum of diglycine barium chloride monohydrate

The Raman spectrum of diglycine barium chloride monohydrate in the single crystal form has been recorded using λ 2536·5 excitation. 43 Raman lines (9 lattice and 34 internal) have been recorded. Satisfactory assignments have been given for most of the observed Raman lines. It is concluded from a comparison of the Raman spectrum of this compound with those of glycine and of other addition compounds of glycine, that the glycine unit exists in the zwitterion form in the structure of diglycine barium chloride monohydrate.

Stability of a cylindrical plasma in the presence of a monotonic field-II

The stability of an incompressible inviscid, perfectly conducting cylindrical plasma against azimuthal disturbances in the presence of a monotonic decreasing magnetic field having a constant pitch is discussed by using energy principle. The results obtained by this principle are compared for m = 1 mode (which is a dangerous mode in which there is a lateral shift of the entire column) with that obtained by normal mode analysis. It is found that m = 1 mode is always unstable. Further, an axial line current, external axial field and the surface tension tend to stabilise m ≠ modes.

Some observations on the behaviour of colchicine-treated cells during recovery in Allium CEPA

The accidental discovery of a cell with haploid number of diplochromosomes in squashes of colchicine-treated root tips led to a search for haploid anaphases in treated roots allowed to recover in water. No haploid anaphases were seen. Apart from the divisional stages of diploid and tetraploid nuclei, cells with two pro-, meta- and ana-phases were observed. The formation of distinct cell boundaries by each nucleus of an originally multinucleate cell indicates their potentialities in this direction.